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/* Copyright (C) 2000-2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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Abort logging when we get an error in reading or writing log files
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#include <drizzled/server_includes.h>
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#include <drizzled/replicator.h>
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#include <mysys/hash.h>
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#include <mysys/my_dir.h>
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#include <drizzled/plugin.h>
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#include <drizzled/error.h>
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#include <drizzled/errmsg_print.h>
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#include <drizzled/gettext.h>
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#include <drizzled/data_home.h>
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#include <drizzled/session.h>
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#include <drizzled/handler.h>
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static const string engine_name("binlog");
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StorageEngine *binlog_engine= NULL;
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Save position of binary log transaction cache.
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binlog_trans_log_savepos()
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session The thread to take the binlog data from
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pos Pointer to variable where the position will be stored
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Save the current position in the binary log transaction cache into
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the variable pointed to by 'pos'
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binlog_trans_log_savepos(Session *, my_off_t *pos)
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class BinlogEngine : public StorageEngine
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BinlogEngine(const string &name_arg)
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: StorageEngine(name_arg,
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HTON_NOT_USER_SELECTABLE | HTON_HIDDEN,
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virtual int close_connection(Session *)
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virtual int prepare(Session *session, bool)
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just pretend we can do 2pc, so that MySQL won't
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real work will be done in DRIZZLE_BIN_LOG::log_xid()
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(void)replicator_prepare(session);
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This function is called once after each statement.
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It has the responsibility to flush the transaction cache to the
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binlog file on commits.
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@param engine The binlog StorageEngine.
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@param session The client thread that executes the transaction.
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@param all This is @c true if this is a real transaction commit, and
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@see StorageEngine::commit
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virtual int commit(Session *session, bool all)
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Decision table for committing a transaction. The top part, the
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*conditions* represent different cases that can occur, and hte
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bottom part, the *actions*, represent what should be done in that
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Real transaction 'all' was true
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Statement in cache There were at least one statement in the
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In transaction We are inside a transaction
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Stmt modified non-trans The statement being committed modified a
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non-transactional table
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All modified non-trans Some statement before this one in the
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transaction modified a non-transactional
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============================= = = = = = = = = = = = = = = = =
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Real transaction N N N N N N N N N N N N N N N N
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Statement in cache N N N N N N N N Y Y Y Y Y Y Y Y
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In transaction N N N N Y Y Y Y N N N N Y Y Y Y
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Stmt modified non-trans N N Y Y N N Y Y N N Y Y N N Y Y
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All modified non-trans N Y N Y N Y N Y N Y N Y N Y N Y
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Action: (C)ommit/(A)ccumulate C C - C A C - C - - - - A A - A
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============================= = = = = = = = = = = = = = = = =
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============================= = = = = = = = = = = = = = = = =
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Real transaction Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
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Statement in cache N N N N N N N N Y Y Y Y Y Y Y Y
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In transaction N N N N Y Y Y Y N N N N Y Y Y Y
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Stmt modified non-trans N N Y Y N N Y Y N N Y Y N N Y Y
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All modified non-trans N Y N Y N Y N Y N Y N Y N Y N Y
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(C)ommit/(A)ccumulate/(-) - - - - C C - C - - - - C C - C
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============================= = = = = = = = = = = = = = = = =
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In other words, we commit the transaction if and only if both of
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the following are true:
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- We are not in a transaction and committing a statement
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- We are in a transaction and one (or more) of the following are
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- A full transaction is committed
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- A non-transactional statement is committed and there is
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Otherwise, we accumulate the statement
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if (all || (!session_test_options(session, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))
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return replicator_end_transaction(session, all, true);
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This function is called when a transaction involving a transactional
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table is rolled back.
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It has the responsibility to flush the transaction cache to the
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binlog file. However, if the transaction does not involve
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non-transactional tables, nothing needs to be logged.
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@param engine The binlog StorageEngine.
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@param session The client thread that executes the transaction.
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@param all This is @c true if this is a real transaction rollback, and
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@see StorageEngine::rollback
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virtual int rollback(Session *session, bool all)
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/* TODO: Fix return type */
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(void)replicator_end_transaction(session, all, false);
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How do we handle this (unlikely but legal) case:
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[transaction] + [update to non-trans table] + [rollback to savepoint] ?
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The problem occurs when a savepoint is before the update to the
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non-transactional table. Then when there's a rollback to the savepoint, if we
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simply truncate the binlog cache, we lose the part of the binlog cache where
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the update is. If we want to not lose it, we need to write the SAVEPOINT
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command and the ROLLBACK TO SAVEPOINT command to the binlog cache. The latter
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is easy: it's just write at the end of the binlog cache, but the former
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should be *inserted* to the place where the user called SAVEPOINT. The
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solution is that when the user calls SAVEPOINT, we write it to the binlog
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cache (so no need to later insert it). As transactions are never intermixed
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in the binary log (i.e. they are serialized), we won't have conflicts with
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savepoint names when using mysqlbinlog or in the slave SQL thread.
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Then when ROLLBACK TO SAVEPOINT is called, if we updated some
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non-transactional table, we don't truncate the binlog cache but instead write
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ROLLBACK TO SAVEPOINT to it; otherwise we truncate the binlog cache (which
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will chop the SAVEPOINT command from the binlog cache, which is good as in
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that case there is no need to have it in the binlog).
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virtual int savepoint_set_hook(Session *session, void *sv)
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binlog_trans_log_savepos(session, (my_off_t*) sv);
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/* Write it to the binary log */
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error= replicator_statement(session, session->query, session->query_length);
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virtual int savepoint_rollback_hook(Session *session, void *)
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error= replicator_statement(session, session->query, session->query_length);
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virtual handler* create(TABLE_SHARE*, MEM_ROOT*)
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this function is mostly a placeholder.
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conceptually, binlog initialization (now mostly done in DRIZZLE_BIN_LOG::open)
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should be moved here.
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int binlog_init(void *p)
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StorageEngine** engine= static_cast<StorageEngine **>(p);
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if (binlog_engine == NULL)
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binlog_engine= new BinlogEngine(engine_name);
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*engine= binlog_engine;
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drizzle_declare_plugin(binlog)
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DRIZZLE_STORAGE_ENGINE_PLUGIN,
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"This is a pseudo storage engine to represent the binlog in a transaction",
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binlog_init, /* Plugin Init */
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NULL, /* Plugin Deinit */
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NULL, /* status variables */
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NULL, /* system variables */
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NULL /* config options */
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drizzle_declare_plugin_end;
added
removed
drizzled/log.cc
